The definitive source for rare cactus collectors

Encyclopedic care guides, species profiles, field number collector logs and everything else you’ll need to know about taking care of your collection.

20
Genera covered
500+
Species profiled
4
Rarity tiers
59,794Records indexed

Field number database

Wild-collection provenance for rare cacti, searchable by collector code, species, or locality.

↳ 59,794 records · 280 collectors · 10,393 GPS points · updated quarterly

59,794
Records
Across all 20 genera
280
Collectors
FR · KK · L · PP · BB
10,393
Coordinates
Plotted on the map
20
Genera
Ariocarpus, Copiapoa, Lophophora, more

A cactus collector field-number database is a tool used to identify wild specimens by searching for collector acronyms and field numbers. For example, FR 207 refers to the 207th plant logged by Friedrich Ritter, a Copiapoa cinerea he found near Taltal, Chile in 1954. Each record traces the plant back to where it was collected (locality), the date collected, and the collector's name, acting as a "birth certificate" for the specimen.

Recent Articles

How Often to Water a Cactus (Not on a Schedule)

How Often to Water a Cactus (Not on a Schedule)

How often to water a cactus depends on the mix, the pot, the light, and the temperature, never on a calendar. The documented checks that tell you when... Plant Care20 min read · Aug 20, 2026

The rarity index

Inside the rarity index

Not all rare cacti are equally rare. Our list of the rarest cactus plants in the world ranks specimens by wild population, cultivation difficulty, and trade availability.

Explore the index
Tier
Availability
Examples
Scarcity
Count
S
Critically rare, almost never available
Aztekium ritteri, Turbinicarpus alonsoi
7 species
A
Very rare, specialist trade only
Ariocarpus agavoides, Copiapoa cinerea
18 species
B
Rare, occasional availability
Ariocarpus fissuratus, Mammillaria luethyi
31 species
C
Uncommon, findable with patience
Astrophytum asterias, Ferocactus glaucescens
50+ species